Approximately two out of every five Americans will develop type 2 diabetes at some point during their adult lives, according to new U.S. government estimates.
The ongoing diabetes and obesity epidemics have combined with ever-increasing human lifespans to raise lifetime risk of type 2 diabetes to about 40 percent for both men and women, said lead study author Edward Gregg, chief of the epidemiology and statistics branch in the division of diabetes translation at the U.S. Centers for Disease Control and Prevention (CDC).
"We weren't necessarily surprised that it increased, but we didn't expect it to increase this much," Gregg said. "Forty percent is a humbling number."
The odds are even worse for certain minority groups. Half of black women and Hispanic men and women are predicted to develop type 2 diabetes during their lifetime, the researchers reported.
Results of the study were published online Aug. 13 in The Lancet Diabetes & Endocrinology.
Although the study didn't separate diabetes by type, the vast majority of people with diabetes have type 2 diabetes, according to the American Diabetes Association. In type 2 diabetes, the body either doesn't produce enough insulin and/or is resistant to the effects of insulin, a hormone needed to use the sugars from foods to fuel the cells in the body and brain.
Obesity is a major risk factor for type 2 diabetes, but it's not the only one. Genes also appear to play a role in the development of type 2 diabetes.
In the current study, researchers evaluated medical information and death certificates for about 600,000 adults between 1985 and 2011, to estimate trends in lifetime risk of diabetes as well as years of life lost to diabetes.
During the quarter-century studied, lifetime risk of type 2 diabetes increased for the average 20-year-old American man, jumping from nearly 21 percent in the late 1980s to just over 40 percent in 2011.
For an average 20-year-old woman, the risk increased from 27 percent in the 1980s to almost 40 percent, the investigators found.
The "diabesity" epidemic is the main driver of these increased risks, said Dr. Minisha Sood, an endocrinologist at Lenox Hill Hospital in New York City.
Doctors have coined the term "diabesity" to reflect the combined effects of the diabetes and obesity epidemics. "They go hand-in hand," she said.
People also are living longer, which makes them more likely to develop diabetes at some point during their lives given the lack of exercise and eating habits of the average American, Gregg and Sood said.